Pumps



June 22, 1965 H. G. WELCH 3,190,233

' PUMPS Filed March 5, 1963 5 seet l FIGJ June 22, 1965 r w c 3,190,233

ruurs Filed March 1963 5 h ets-Sheet 2 rrn H. G. WELCH June 22, 1965PUMPS 5 Sheets-Sheet 3 Filed March 5, 1963 June 22, 1965 PUMPS FiledMarch 5, 1963 H. G. WELCH 5 Sheets-Sheet 4 June 22, 1965 H. G. WELCH3,190,233

PUMPS Filed March 5, 1963 5 Sheets-Sheet 5 FIG.6

INVENTOR. HAROLD GEORGE WELCH ATTORNEY United States Patent 3,1tl,233FUR ES Harold George Welsh, Sanderling, Moodys Boat Yard, LowerSwanwiclr, Hampshire, England Filed Mar. 5, 1963, Ser. No. 263,683 6Claims. (Cl. 193-159) This invention relates to pumps and particularlyto reciprocating fluid (liquid or gas) pumps having one or more pairs ofpistons mounted for reciprocation in a common cylinder.

In such pumps the pistons are normally operatively connected to a crankor eccentric in phase with one another or else 180 out of phase. Thisresults in the one case in one of the pistons moving upon its inductionor intake stroke. over the same angle as the other piston moves upon itsexhaust or output stroke, whilst in the other case the two pistons moverover the same angles upon their respective intake and output strokes.Either of these prior arrangements therefore requires that aconsiderable driving force should be applied to the pistons by the crankover certain partsof the cycle of revolution of the crank, whilst atother points in the cycle very little or no driving force is required.This variation in the required driving force results in much higher wearof the working parts of the pump. Moreover, since the power to drivesuch a pump is normally applied in the form of a substantially constanttorque, and this torque must always be greater than the maximum requiredto drive the piston over the part of the cycle where the loading isgreatest, the power required is much greater than if the loading of thepistons were to be equal over the entire cycle of the crank. Thisdisadvantage can, of course, be overcome tosome extent by the use of aflywheel in the pump drive, but this can only result in a limited powersaving, since the starting torque of the driving means has to besuficient to overcome the inertia of the flywheel. 7

Even where pumps are to be manual instead of mechanically operated,these disadvantages still apply, since a pump in which the manual effortrequired varies over the cycle of the pump is more diflicult'to operatethan one in which the effort called for is constant.

It is object of the present invention to provide a construction of pumpwhich overcomes these disadvantages.

According to the invention a pump is provided hava pair of pistonsmounted for reciprocation in a common cylinder in which each piston isconnected by a single connecting rod to a common crankshaft at a phasedifference such that the maximum driving torque required in respect ofone of the pistons in coincidence with the minimum driving torquerequired in respect of the other of said pistons.

This condition may be obtained by connecting the pistions to a commoncrank shaft at a phase difierence of approximately 60.

In further accord with the invention a pump is provided having a pair ofpistons reciprocable with a common cylinder, each piston being connectedby a single connecting rod to a common crank shaft at a phase differenceof approximately 60,in which the phase between the pistons is utilizedas an operative part of the pump in addition to the end spaces beyondeach of the' hlhdihi whilst at the same time evening out the thrustwhich is required to drive it.

U'illiZlIl" this arrangement with the connecting rods from each of thepistons being connected to a common crank shaft as points separated byabout 60, a pump may be provided in which the driving torque required issubstantially constant throughout the whole of its cycle.

The general construction of the pump" and the manner of driving it maybe the same as that which is conventionally utilized in constructions ofapparatusof thiskind.

Conveniently the valve assembly for use with a pump according to theinvention may be arranged such that each of the three operative spaceswithin the cylinder is exposed to individual inlet and outlet valveswhich may be lightly spring-loaded into place and which when closed areheld firmly against their seatings by the fluid pressure.

' Thus, from each of the operative regions of the cylinder a port in thecylinder wall may connect with a compartment in a valve chest. Thiscompartment may. be provided with two ports, one, leading to a commoninlet duct whilst the other leads to a common outlet duct, and each ofthese ports may be closed by a suitable form of valve which is normallyheld lightly in the closed position'by a low rate spring (the exact rateof which will be chosen according to the characteristics of the liquidor gas to be pumped). During the suction or inlet stroke in theappropriate region of the cylinder, the inlet valve is lifted from itsseat against the force of its spring by the suction or negative pressurecreated, whilst during this stroke the outlet valve is held very firmlyin its seating by the same pressure differential. During the outletstroke, the inlet valve is pressed firmly against its seating by thepressure of the outgoing fluid, whilst the outlet valve is liftedagainst the force of its spring.

With the foregoing and other objects in view which will appear asthedescription proceeds, the invention resides in the combination andarrangement of parts and in the details of construction hereinafterdescribed and claimed, it being the intention to cover all changes andmodifications of the example of the invention herein chosen for purposesof the disclosure, which do not constitute departures from the spiritand scope of the invention.

The invention is illustrated in the accompanying drawings, wherein:

FIGURE 1 is a side elevational view of a pump in accordance with thisinvention.

FIGURE 2 is a left hand end view.

FIGURE 3 is a vertical section on line llIlIl of FlG- URE 2.

FIGURE 4 is a vertical section on line IVIV of FIG- URE 1.

FIGURE 5 is a horizontal section on line VV of FIGURE 1.

FIGURE 6 is a vertical section comparable with FIG- 7 caps 15 andcontaining two pistons 16 and 17 arranged to be reciprocated by therotation of a driving shaft 18 located transversely of the casing 11 onthe axial center line of said common cylinder 14. The pistons 16 and i7Patented June 22, 1955 V 1 an outlet chamber 26.

V chamber 26.

may be in the form of cups of nylon or a similar material and areconnected to a commoncrankshaft mounted on the driving shaft 18, theconnections to the common crankshaft being at a phase difference suchthat the maximum driving torque required inrespcct ofone of the pistonsis coincident with the minimum driving torque required in respect ofthey other of said pistons.

The driving shaft 18 extending through the righthand side of thecylinder 14 as viewed in FIGURE 4has opposed thereto in the lefthandside of the cylinder 14 a short shaft portion 18, this short shaftportion being coupied to the common crank shaft 18. The short shaftportion 18 is rotatably housed in a projection 2 of the cylinder casing14, said projection 2 being closed by a closure plug 34. The space 19,to the left of the left hand piston communicates permanently with achamber 29 in the valve chest 13 (see FrGURE 3), the space 21 betweenthe of righthand piston 1'7 with a chamber 24. a

Each of the three chambers 20, 22 and 24, when subjected in turn to areduced pressure by the pistons, communicate with an inlet chamber 25,FIGURES 4 and 5, and when the three chambers 20, 22' and 24 aresubjected in turn to pressure by the piston they communicate with Thechamber 25 is permanentlymonnec tedto an inlet pipe 27 and the chamber26 is permanently connectedto an outlet pipe 28. i

The manner in which the chambers 29, 221and 24 l communicate with theinlet and outlet chambers ZS-and Z6 is determined by pressureoperatedvalves. a

There are six of these pressure operated valves, arranged in pairs, onepair for each of chambers 29, 22 and .24 and of each pair one valvecommunicates with chamber 25 and the other with chamber 26. Thus, thereare three transverse fixed spindles, of which FIGURE 4 shows the spindle29 pertaining to chamber 22. On'each spindle. are mounted two valvediscs 30 and 31,-spring-'ur"ged-infthe same direction, to the left ,asviewed in FIGURE'4,'tor wards'closure on respective seatings32 and,33..The ends of each of the three transverse-spindles, such as spindle 29,are screw threaded so that end ca'ps.3', with correspondingly threadedend portions 4, can be screwed onto the spindles to seal circularopenings 5 that lead into the chambers 20, 2t and 24 from both sides ofthe valve chest 13. The spring 6 that acts on the valve disc 31 iscompressed between he valve disc 31 and the righthand end cap 3 shown inFIGURE 4. T he spring 7. that pistons with a chamber 22, and the space23 to the right V contaminate the fluid being pumped since the grease isoutside the sealing ring. 1

acts on the valve disc 39 i compressed between the valve disc 30 and acollar 8 that is spaced from .the righthand end cap 3 by a sleeve9 onthe spindle 29, the valve disc intermediate spaced 21 varies in Volume,As the volume of a space is enlarged, incoming fluidpressure in chamberopens the inlet valve in thecase of the intermediate space 21 and itschamber 22) against its spring pressure, to admit the fluid to thespace. As the space contracts in volume, valve 30 closes and outletvalve 31 opens to discharge the fluid at a heightened pressure to theoutlet By this means a pump is provided in which a fluid, which may be aliquid or which may be a gas, is drawn into the chamber 25 through asupply conduit 27 and passed out from the outlet chamber 26 through anoutlet conduit 28 at an almost completely steady rate, very littlepulsation being apparent in the flow. Moreover,thc torque required todrive the shaft 18 is almost exactly the same throughout the entire 360of its cycle of revolu tion. Thus, a pump is provided which is veryeasily driven and which, if it is driven by a motor, requires a muchlower power motor than would a conventional pump delivering the samevolume of fluid at the same pressure. Where the pump i to be handoperated, a handle a carried upon the shaft 18 can be rotated with verymuch less fatigue than in the case of a conventional pump since thepressure which must be applied to the handle is constant throughout thecycle and does not vary.

Since the chamber 21 containing the cranks and bean quick removal of thevalve units 29, 30 and 31 for cleaning of any stoppages which mightoccur, since it is only neces-. sary forthe lefthand cover of any of thethree valve cham-. bers 20, 22 and 24 to be removed whereupon, when therighthand cover of that. chamber is removed, the. whole valve system inthat chamber can be Withdrawn. Moreover, since the valve chest 13 isabove the cylinder 14 the need for a bleeder valve is avoided.

The closure plug 34 shown in FIGURE4 can be. rej-i moved to give accessto the short shaft portion18'=so that the pump can be driven from eitherside.

It should be noted that the .end covers 15 may be of the flanged typewith sealing rings betwceneach flange and the cylinder casting 11, butto reduce cost the end covers 15 are preferably threaded plug typeclosures asshown, with the sealing ring sandwiched between'the 7 end ofthe cover 15 and the wall of a counterbase in the cylinder casting 11.This ensures that any grease used to protect the screw thread of the endcaps 15 does not It will be appreciated that the actual construction ofthe pump may be varied considerably from the specific construction whichis shown in the drawings without departing from the invention. Inparticular, the two halves of the cylinder in' which .the two pistonsmove may conconnections and reducing the tendency of the pistons totwist out of alignment with the cylinder bores. In FIG- URE 6 the twohalves of the cylinder are indicated by the numerals 35 and 36respectively and the crankshaft is indicated by the numeral 37..

The pump may be madein any desired materials and in any desired size. Itwill be appreciated that where it is intended for use with gases orfluids of low viscosity, the spring rates controlling the valves willneed to be considerably different from those which will be requiredwhere the pump is used with relatively viscous liquids. 7

Having thus described my invention, what I claim is: 1. A pump having acylinder with closed ends in a common casing with a valve chest, a pair.of pistons reciprocable within saidcylinder, a crank shaft in saidcylinder between said piston-s, connecting rods connecting each of saidpistons to said crank shaft: at a phase diifence of approximately thespace within said cylinderbe tween the. pistons being sealed andcomprising an operative'part of the pump in addition to the end spacesbe 2. A pump having two cylinders arranged in oppositely disposedrelation with axes parallel, a crank shaft in said pump between saidcylinders, a pistonmounted for recip i rocation in each of saidcylinders, straight connecting rods.

connecting said pistons withrsaid crank shaft, said cylint ders'beingoffset to such a degree as to allow the-use of said straight:connecting. rods extending between said crank shaft and the centersofsaid pistons, a valve chest positioned adjacent said two cylinders andaccessports in said two cylinders establishing communication therewith,

pressure operated valves in said access ports and wherein said twocylinders and casing are completely sealed except for said access ports.

3. A pump having a common cylinder, a pair of pistons mounted forreciprocation in said common cylinder at a phase difierence such thatthe maximum driving efiort required in respect of one of said pistons iscoincident with the minimum driving effort required in respect of theother of said pistons, and wherein the space between the pistons issealed and operative as a pumping space in addition to spaces beyond thepistons within the cylinder, a common crank shaft within said pumpintermediate the pistons, and a pair of connecting rods respectivelyconnecting said pistons to said crank shaft at said phase difference, avalve chest disposed alongside said common cylinder, and three accessports in the wall thereof each serving as a common inlet and outletconnection between a respective one of the pumping spaces, and the valvechest, pressure responsive valves in each of said three access ports.

4. A pump according to claim 3 and wherein said phase difference isequal to 60.

5. A pump according to claim 3 and wherein said valve chest has a commoninlet compartment and a common outlet compartment and wherein'saidpressure responsive valves comprise a pressure-operated inlet valveassociated with each of said chambers and serving to establishcommunication between a respective one ofsaid chambers and said commoninlet compartment within the valve chest, and a pressure-operated outletvalve associated with each of said chambers and serving to establishcommunication between a respective one of said chambers and said commonoutlet compartment at appropriate times during a pumping cycle.

6. A pump according to claim 3 wherein said valve chest has a commoninlet compartment and a common outlet compartment and wherein saidpressure operated valves comprise a pressure-operated inlet valveassociated with each of said chambers and serving to establishcommunication between a respective one of said chambers and 7 saidcommon inlet compartment within the valve chest, and a pressure-operatedoutlet valve associated with each of said chambers and serving toestablish communication between a respective one of said chambers andsaid common outlet compartment at appropriate times during a pumpingcycle, three static spindles arranged within the valve chesttransversely of the cylinder, each of the spindles passing through arespective one of said chambers, a pair of valve discs slidable on eachof said spindles and respectively constituting said inlet valve and saidoutlet valve, spring means urging each of said ,valve discs into aclosed position, and end caps removable from without and detachablyreceiving the ends of each of said spindles, so that said valves can beeasily withdrawn from the valve chest when desired.

References Cited by the Examiner UNITED STATES PATENTS 591,137 10/87Miles 230-211 793,341 6/05 Belknap 103-177 1,060,160 4/13 Butler 103-1651,183,973 5/16 Hewitt 103-171 1,388,780 8/21 Stanley 103176 1,566,62012/25 Scoville 230--l X 2,083,073 6/37 Loeber 103-171 X 2,198,722 4/40Horvath 103 -41 FOREIGN PATENTS 555,900 4/23 France.

LAURENCE V. EFNER, Primary Examiner.

WARREN E. COLEMAN, Examiner.

1. A PUMP HAVING A CYLINDER WITH CLOSED ENDS IN A COMMON CASING WITH AVALVE CHEST, A PAIR OF PISTONS RECIPROCABLE WITHIN SAID CYLINDER, ACRANK SHAFT IN SAID CYLINDER BETWEEN SAID PISTONS, CONNECTING RODSCONNECTING EACH OF SAID PISTONS TO SAID CRANK SHAFT AT A PHASE DIFFENCEOF APPROXIMATELY 60*, THE SPACE WITHIN SAID CYLINDER BETWEEN THE PISTONSBEING SEALED AND COMPRISING AN OPERATIVE PART OF THE PUMP IN ADDITION TOTHE END SPACES BEYOND EACH OF THE PISTONS AND THE CLOSED ENDS OF SAIDCYLINDER, ACCESS PORTS IN SAID COMMON CYLINDER ESTABLISHINGCOMMUNICATION BETWEEN SAID VALVE CHEST AND SAID COMMON CYLINDER,PRESSURE OPERATED VALVES CONTROLLING SAID ACCESS PORTS, AND WHEREIN SAIDCOMMON CASING IS COMPLETELY SEALED EXCEPT FOR SAID VALVED ACCESS PORTS.